Remote Desktop Control has 2 connectivity modes: "Direct Connection" and "Internet Gateway Account Connection"
This mode lets you connect to the remote PC using DNS name or IP address.
Successful connection is possible only when Host PC has static external IP address and proper firewall/router configurations or when both Admin and Host computers are located in the same LAN.
This mode lets you connect with remote PC via Internet in the case when Host PC has no external IP address (for example, Host is located in the private LAN behind the router). Using this mode you are not obliged to know remote IP address as you connect via Account name and computer nickname instead of IP address. This mode works without changing any settings of the firewall/router.